Tape cartridge reel lock mechanism

ABSTRACT

A magnetic tape cartridge, particularly for use in a digital audio tape player, which includes a lock mechanism for avoiding an arbitrary motion of any one of the reels within the cartridge so as to avoid an undesirable loosening of a length of the magnetic tape extending between the reels, the lock mechanism including a lock member normally biased to a lock position and having lock pawls normally engaged with toothed lock wheels integral with the respective reels, at least one stopper rod protruding from one end of the lock member and terminating in alignment with a free end of a corresponding one of hinge arms integral with a front cover used to selectively open and close a front opening of the cartridge such that so long as the front cover is in position to close the front opening, the free end of the stopper rod is positioned in close proximity to the corresponding hinge arm to keep the lock member immovable even when a drastic impact acts on the tape cartridge tending the lock member to move from the locked position towards an unlocked position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a tape cartridge accommodating a rolledlength of magnetic recording tape and, more particularly, to a tapecartridge having a reel lock mechanism to keep reels immovable when thetape cartridge is not in use.

2. Description of the Related Art

DAT tape cartridges, that is, tape cartridges specifically designed foruse with a digital audio tape (DAT) player, are generally provided witha reel lock mechanism to keep reels immovable when the tape cartridge isnot in use. This type of reel lock mechanism is disclosed in, forexample, Japanese Laid-open Utility Model Publication No. 63-191483,published in 1988, and this known reel lock mechanism will now bediscussed with the aid of FIG. 20a and 20b of the drawings annexedhereto.

As is well known, the tape cartridge of the type to which the presentinvention pertains is generally standardized in size and configurationso that it can be used with the commercially available digital audiotape player. This tape cartridge comprises a generally rectangularbox-like casing 1 including rectangular top and bottom walls and aperipheral wall disposed between the top and bottom walls to keep thetop and bottom walls spaced apart a distance enough to accommodate alength of magnetic recording tape within the casing, the peripheral wallincluding a hingedly supported front wall section or front cover 6, arear wall section opposite to the front cover and a pair of side wallsections, all assembled together with the top and bottom walls to renderthe cartridge to represent a generally rectangular, generally flattenedbox-like configuration.

In practice, the casing 1 is divided into two casing halves along aplane generally intermediate of the thickness of the peripheral wall.

within the casing 1, there is disposed a pair of freely rotatable reels3, each generally in the form of a cylindrical hub, to which oppositeends of the length of magnetic recording tape 2 are anchoredrespectively, and a pair of guide rollers 5 rotatably disposed withinthe casing 1 at respective corner areas adjacent the front cover 6 so asto permit a portion of the length of magnetic recording tape 2 betweenthe guide rollers 5 to extend generally parallel to the front cover 6.

As shown in FIGS. 20a and 20b, the reel lock mechanism employed in theprior art DAT tape cartridge is housed within the casing 1 and iscooperable with any one of toothed lock wheels 8 each formed integrallywith one end of the associated reel 3. This reel lock mechanism includesa generally elongated, thin-walled lock member 9 extending widthwise ofthe casing 1 and between the opposite side wall sections of the casing 1for movement between unlocked and locked positions in a directionperpendicular to the lengthwise direction of the lock member 9. The lockmember 9 has lock pawls 11 formed integrally therewith so as to protrudeoutwardly therefrom for engagement with the corresponding toothed lockwheels 8 integral with the respective reels 3.

The lock member 9 is normally biased towards the lock position by a wirespring 10 and has its opposite ends connected or integrally formed withrespective traction arms 12 extending perpendicular to the lock member9. Respective free ends of the traction arms 12 are operativelyassociated with the front cover 6 so that, when the front cover 6 isopened to allow that portion of the length of magnetic recording tape 2to be exposed to the outside, the lock member 9 can be retraced againstthe resiliency of the wire spring 10 towards the unlock position withthe lock pawls 11 consequently disengaging from the associated toothedlock wheels 8, but when the front cover 6 is closed to conceal thatportion of the length of magnetic recording tape 2, the lock member 9can be urged by the wire spring 10 to the lock position with the lockpawls 11 consequently engaged with the toothed lock wheels 8.

To operatively couple the free ends of the front cover 6, respectivehinge arms 6b protruding transversely from opposite ends of the frontcover 6 have their inner surfaces formed with associated operating ribs16. So long as the lock member 9 is held in the lock position, the lockpawls 11 are engaged with the associated toothed lock wheels 8 integralwith the reels 3 and, therefore, the reels 3 are held immovable to avoidany possible loosening of the length of magnetic recording tape 2.

With the reel lock mechanism wherein the biasing force of the wirespring 10 is utilized to keep the lock member 9 in the lock position,the lock pawls 11 integral with the lock member 9 will not disengagefrom the associated toothed lock wheels 8 so long as the tape cartridgeis handled normally. However, when an excessive external force such asan impact on the tape cartridge as a result of, for example, anaccidental fall of the tape cartridge onto an indoor or outdoor groundsurface, the reels 3 may be instantaneously rattled enough to cause thelock member 9 to be undesirably displaced against the resiliency of thewire spring 10. Once this occur, the lock pawls 11 are disengaged fromthe associated toothed lock wheels 8, permitting the reels 3 to rotateidle, resulting in a loosening of the length of magnetic recording tape2 that is turned around those reels 3.

When the tape cartridge in which the length of magnetic recording tape 2has been loosened in the manner described above is loaded into a digitalaudio tape player, the length of magnetic recording tape may beundesirably bent and/or caught by loading pins employed in the digitalaudio tape player to pull that portion of the length of magneticrecording tape outwardly from the casing, eventually resulting in adetrimental problem in that the tape cartridge may be no longer usableand/or a tape loading mechanism in the digital audio tape player may beimpaired.

SUMMARY OF THE INVENTION

The present invention is therefore intended to provide an improved tapecartridge wherein, even though an external force such as an impact actson the tape cartridge, the lock member will not be undesirably displacedtowards the unlock position unless the front cover is operated, therebyto avoid any possible undesirable loosening of the length of magneticrecording tape within the tape cartridge when the tape cartridge is notin use.

To this end, the present invention provides a tape cartridge whichcomprises a generally rectangular box-like casing including rectangulartop and bottom walls, a pair of side walls and a rear wall, allassembled together to represent a generally rectangular flat box-likeconfiguration with a tape chamber defined therein, and having a frontopening defined therein so as to confront the rear wall. The casing alsoincludes a front cover hinge supported having a pair of hinge armspivotally coupled to the respective side walls for pivotal movementbetween an opened position, in which the front cover opens the frontopening, and a closed position in which the front cover closes the frontopening.

First and second reels are rotatably housed within the tape chamber,opposite ends of the length of magnetic tape being secured to the firstand second reels, respectively. Each reel has a toothed lock wheelrotatable together therewith.

The tape cartridge also comprises a hub lock mechanism housed within thetape chamber and including a generally elongated lock member movablebetween locked and unlocked positions in a direction transverse to thefront cover, and a spring element for biasing the lock member towardsthe locked position. The lock member has lock pawls engageable with thetoothed lock wheels to lock the respective reels when the lock member isin the lock position and also has traction arms protruding from oppositeends of the lock member in a direction perpendicular to the lock memberand towards the hinge arms, the traction arms being operatively coupledwith the hinge arms such that, as the front cover is pivoted from theclosed position towards the opened position, the lock member is pulledfrom the lock position towards the unlock position against the springelement.

The tape cartridge further comprises at least one stopper rod protrudingfrom a corresponding one of the opposite ends of the lock member in adirection perpendicular to the lock member and towards the front openingin alignment with a corresponding one of the hinge arms, the stopper rodhaving a free end positioned in close proximity of a free end of thecorresponding hinge arm, when the front cover is in the closed positionthereby to keep the lock member immovable.

A lateral displacement suppressing means may be employed in the tapecartridge of the present invention. This lateral displacementsuppressing means may be defined in part in the free end of the stopperrod and in part in the free end of the corresponding hinge arm foravoiding a deformation of stopper rod inwardly of the casing.

Preferably, the lateral displacement suppressing means may comprise afirst lateral engagement defined in the free end of the stopper rod anda second lateral engagement defined in the free end of the correspondinghinge arms, the first and second lateral engagements being laterallyoffset in position relative to each other with respect to a longitudinalaxis of any one of the stopper rod and the corresponding hinge arm.

Alternatively, the lateral displacement suppressing means may comprise afirst inclined face defined at the free end of the stopper rod and asecond inclined face defined at the free end of the corresponding hingearm, the first and second inclined faces being complemental to eachother and inclined relative to a longitudinal axis of any one of thestopper rod and the corresponding hinge arm.

Also alternatively, the lateral displacement suppressing means maycomprise a protuberance protruding outwardly from one of the free endsof the stopper rod and the corresponding hinge arm and a pocket definedin the other of the free ends of the stopper rod and the correspondinghinge arm for receiving the protuberance therein.

Preferably, the casing may include an inner side wall segment forrestricting an inward displacement of any one of the stopper rod andeach hinge arm when the front cover is in the closed position.

Also preferably, the casing may include an outer side wall segment forrestricting an outer displacement of any one of the stopper rod and eachhinge arm when the front cover is in the closed position.

Again preferably, the tape cartridge may further comprise a generallyU-sectioned slider forming a front area of the bottom panel andsupported for movement in a direction perpendicular to the front coverfor selectively opening and closing a bottom region of the frontopening, the slider having upright side wall elements aligned with therespective hinge arms integral with the front cover, each of the sidewall elements having a first engagement defined therein while each ofthe hinge arms has a second engagement defined therein for engagementwith the first engagement to prevent the hinge arms from being outwardlydeformed.

BRIEF DESCRIPTION OF THE DRAWINGS

This and other objects and features of the present invention will becomeclear from the following description taken in conjunction with preferredembodiments thereof with reference to the accompanying drawings, inwhich like parts are designated by like reference numerals and in which:

FIG. 1 is a side view, with a portion broken, of a tape cartridgeaccording to a first preferred embodiment of the present invention;

FIG. 2 is a perspective view of the tape cartridge according to thefirst preferred embodiment of the present invention;

FIG. 3(a) is a top plan view, with the top wall removed, of the tapecartridge of FIG. 1 showing interior component parts thereof;

FIG. 3(b) is a fragmentary top sectional view, on an enlarged scale, ofthat portion of the tape cartridge which is enclosed in a circle shownin FIG. 3(a);

FIG. 4 is a perspective view showing a reel lock mechanism employed inthe tape cartridge according to the first preferred embodiment of thepresent invention;

FIG. 5 is a fragmentary perspective view showing the details of one sidecorner of the tape cartridge according to the first preferred embodimentof the present invention;

FIG. 6 is a fragmentary side view, with a portion cut away, of the tapecartridge according to a second preferred embodiment of the presentinvention;

FIG. 7 is a cross-sectional view taken along the line A--A in FIG. 6;

FIG. 8(a) is a perspective view of the reel lock mechanism employed inthe tape cartridge according to the second preferred embodiment of thepresent invention;

FIG. 8(b) is a fragmentary top sectional view, on an enlarged scale, ofthat portion of the tape cartridge which is enclosed in a circle shownin FIG. 8(a);

FIG. 9(a) is a perspective view of a front cover employed in the tapecartridge according to the second preferred embodiment of the presentinvention;

FIG. 9(b) is a fragmentary top sectional view, on an enlarged scale, ofthat portion of the tape cartridge which is enclosed in a circle shownin FIG. 9(a);

FIG. 10 is an exploded view, on an enlarged scale, showing the detailsof one of front corners of the tape cartridge according to the secondpreferred embodiment of the present invention;

FIG. 11 is a view similar to FIG. 7, showing the tape cartridgeaccording to the second preferred embodiment of the present invention;

FIG. 12 is a fragmentary side view, with a portion cut away, of the tapecartridge according to a third preferred embodiment of the presentinvention;

FIG. 13 is a cross-sectional view taken along the line B--B in FIG. 12;

FIG. 14 is a fragmentary side view, with a portion cut away, of the tapecartridge according to a fourth preferred embodiment of the presentinvention;

FIG. 15 is a cross-sectional view taken along the line C--C in FIG. 14;

FIG. 16 is a fragmentary side view, with a portion cut away, of the tapecartridge according to a fifth preferred embodiment of the presentinvention;

FIG. 17 is a cross-sectional view taken along the line D--D in FIG. 16;

FIG. 18 is a fragmentary side sectional view of the tape cartridge,showing a modified form of the front cover and a slider; and

FIG. 19 is a fragmentary side sectional view of the tape cartridge,showing another modified form of the front cover and the slider.

FIG. 20(a) is a top plan view, with the top wall removed, of a tapecartridge of the prior art; and

FIG. 20(b) is a fragmentary to sectional enlarged view of that portionof the tape cartridge enclosed in the circle of FIG. 20(a).

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1, 2, 4 and 5 showing a first preferredembodiment of the present invention, the tape cartridge shown therein isso designed and so structured as to meet the DAT standards so that itcan be used with the commercially available digital audio tape player ofany make. This tape cartridge comprises a generally rectangular box-likecasing 1. The casing 1 includes rectangular top and bottom walls and aperipheral wall disposed between the top and bottom walls to keep thetop and bottom walls spaced apart a distance enough to accommodate alength of magnetic recording tape 2 within the casing 1 and including ahinged supported front wall section or front cover 6, a rear wallsection opposite to the front cover and a pair of side wall sections,all assembled together with the top and bottom walls to render thecartridge to represent a generally rectangular, generally flattenedbox-like configuration.

In practice, the casing 1 is comprised of upper and lower casing halves1a and 1b separate from each other along a plane generally intermediateof the thickness of the peripheral wall, which casing halves 1a and 1bare placed one above the other and then bonded or rigidly connectedtogether to complete the casing 1.

Within the casing 1, there is disposed a pair of freely rotatable reels3, each generally in the form of a cylindrical hub, to which oppositeends of the length of magnetic recording tape 2 are anchoredrespectively, and a pair of guide rollers 5 rotatably disposed withinthe casing 1 at respective corner areas adjacent the front cover 6 so asto permit a portion of the length of magnetic recording tape 2 betweenthe guide rollers 5 to extend generally parallel to a plane of atransverse front window 4 adapted to be selectively opened and closed bythe front cover 6. In practice, the length of magnetic recording tape 2when the tape cassette is in use within the digital audio player travelsfrom one reel 3 to the other reel 3 via the guide rollers 5 with thatportion of the magnetic recording tape 2 pulled outwardly through thetransverse front window 4 for sliding engagement with a magneticrecording and/or reproducing head. At this time the front cover 6 isheld in an open position to permit that portion of the length ofmagnetic recording tape 2 to be pulled outwardly through the transversefront window 4.

The front cover 6 includes a generally elongated front flap 6a extendinga distance sufficient to close the entire width of the front window 4and hinge arms 6b secured to, or otherwise formed integrally with,respective opposite ends of the front cover 6 so as to protrudetransversely therefrom. Free ends of the hinge arms 6b remote from thefront flap 6a are pivotally connected to the side wall sections of thecasing 1 by means of associated pivot pins 15 so that the front cover 6can pivot about a common axis of the pivot pins 15 between a closedposition, in which the front window 4 is closed to protect that portionof the length of magnetic recording tape, and an opened position inwhich that portion of the length of magnetic recording tape 2 is exposedto the outside through the front window 4. It is, however, to be notedthat the front cover 6 is normally biased by a spring element (notshown) so as to assume the closed position.

The tape cartridge carries a slider 7 which forms a front part of thebottom wall thereof adjacent the transverse front window 4 and which issupported for movement in a direction perpendicular to the widthwisedirection of the casing 1 for selectively opening and closing a bottomregion of the transverse front window 4. This slider 7 is normallybiased by a biasing spring 17 towards a projected position to close thebottom region of the transverse front window 4.

A reel lock mechanism operable to avoid an arbitrary rotation of any oneof the reels 3 within the casing 1 when the tape cartridge is not in useis housed within the casing 1 and cooperates with any one of toothedlock wheels 8 each formed integrally with one end of the associated reel3.

This reel lock mechanism includes a generally elongated, thin-walledlock member 9 extending widthwise of the casing 1 and between theopposite side wall sections of the casing 1 for movement betweenunlocked and locked positions in a direction perpendicular to thelengthwise direction of the lock member 9. The lock member 9 has lockpawls 11 formed integrally therewith so as to protrude outwardlytherefrom for engagement with the corresponding toothed lock wheels 8integral with the respective reels 3.

The lock member 9 is normally biased towards the lock position by a wirespring 10 and has its opposite ends connected or integrally formed withrespective traction arms 12 extending perpendicular to the lock member9. Respective free ends of the traction arms 12 are operativelyassociated with the front cover 6 so that, when the front cover 6 isopened to allow that portion of the length of magnetic recording tape 2to be exposed to the outside, the lock member 9 can be retraced againstthe resiliency of the wire spring 10 towards the unlocked position withthe lock pawls 11 consequently disengaged from the associated toothedlock wheels 8, but when the front cover 6 is closed to conceal thatportion of the length of magnetic recording tape 2, the lock member 9can be urged by the wire spring 10 to the lock position with the lockpawls 11 consequently engaged with the toothed lock wheels 8.

As best shown in FIG. 4, the lock member 9 is made of plastic by the useof a plastics molding techniques and is therefore of one-piececonstruction including side plates 9a and a generally elongated,thin-walled bridge plate 9b extending between the side plates 9a, lockpawls 11 positioned generally intermediate of the length of the bridgeplate 9b and protruding laterally outwardly therefrom so as to confrontthe associated toothed lock wheels 8, and traction arms 12 protrudingfrom the respective side plates 9a in a direction counter to thedirection of extension of the lock pawls 11 and positioned offsetrelative to the bridge plate 9b. Respective free ends of the tractionarms 12 are formed integrally with engagement pawls 13 protrudinglaterally outwardly in respective directions opposite to each other.

The lock member 9 also includes stopper rods 14 secured to therespective side plates 9a at a location intermediate between the bridgeplate 9b and the traction arms 12 so as to protrude parallel to theassociated traction arms 12 in a direction conforming to the directionof extension of the traction arms 12, but terminating a distanceinwardly from the free ends of the traction arms 12. Since the lockmember 9 is normally biased by the wire spring 10 towards the lockposition as briefly described, the bridge plate 9b has a pair of fingers9c formed therein at a location generally intermediate of the length ofthe bridge plate 9b so as to confront in a direction counter to thedirection of extension of the lock pawls 11 for engagement with oppositeends of the wire spring 10 while the wire spring 10 having anintermediate eye defined therein is supported in position with the eyemounted on a support boss 18 integral with the top wall of the uppercasing half 1a.

As best shown in FIG. 5, to operatively couple the front cover 6 withthe lock member 9, the hinge arms 6b of the front cover 6 which protrudetransversely from opposite ends of the front cover 6 have their innersurfaces formed with associated operating ribs 16. So long as the lockmember 9 is held in the lock position as biased by the wire spring 10,the lock pawls 11 are engaged with the associated toothed lock wheels 8integral with the reels 3 to keep the reels 3 immovable thereby to avoidany possible loosening of the length of magnetic recording tape 2 withinthe casing 1. At this time, the front cover 6 is held in the closedposition, in which condition respective free end faces of the hinge arms6b remote from the front flap 6a are held in contact with side walls 7bof the slider 7, as shown in FIG. 2. The condition shown in FIG. 2illustrates when the tape cartridge is not in use.

Referring still to FIG. 5, the stopper rods 14 secured to the respectiveside plates 9a of the lock member 9 have their free end portions exposedto the outside of the casing 1 through associated side openings 19defined at stepped shoulders in opposite side walls of the upper casinghalf 1a. The stopper rods 14 are so sized and so configured that, whenand so long as the lock member 9 is held in the lock position with thefront cover 6 held in the closed position, respective free ends of thestopper rods 14 terminate at a location spaced a distance from theassociated free end faces of the hinge arms 6b of the front cover 6while forming a gap G therebetween, as best shown in FIG. 3(b). The gapsG between the free ends of the stopper rods 14 and the free end faces ofthe hinge arms 6b of the front cover 6 are secured for the purpose ofpermitting the front cover 6 to pivot from the closed position towardsthe opened position without receiving any resistance which would beimposed on the front cover 6 if a sliding contact took placetherebetween. Care must, however, be taken that any movement of the lockmember 9 integral with the stopper rods 14 over the distancecorresponding to each gap G does not result in a disengagement of thelock pawls 11 from the associated toothed lock wheels 8 integral withthe reels 3. This can be accomplished by choosing the size of each gap Gto a value smaller than the depth of engagement of each lock pawl 11into any one of the tooth grooves in the respective toothed lock wheel8.

The provision of the stopper rods 14 in the lock member 9 as describedhereinabove is effective to avoid an undesirable movement of the lockmember 9 towards the unlock position while the front cover 6 is held inthe closed position, that is, while the tape cartridge is not in use,because a corresponding movement of the stopper rods 14 is barred by thefree end faces of the hinge arms 6b of the front cover 6 then held inthe closed position. In other words, even though the lock member 9 tendsto move towards the unlocked position against the resiliency of the wirespring 10 under the influence of an external force, such as an impactacting on the tape cartridge as a result of, for example, a fall of thetape cartridge onto a ground surface, or even though an arbitrary motionof one or both of the reels 3, as a result of the application of theexternal force thereto, tends to cause the lock member 9 to move towardsthe unlock position, the movement of the lock member 9 over the distancewhich would result in the disengagement of the lock pawls 11 from theassociated toothed lock wheels 8 is hampered by the engagement of thefree ends of the stopper rods 14 against the free end faces of the hingearms 6b of the front cover 6 then held in the closed position.Therefore, so long as the front cover 6 is held in the closed position,that is, the tape cartridge is not in use, the reels 3 canadvantageously be locked in position with the lock pawls 11 engaged withthe associated toothed lock wheels 8 integral with the reels 3.

On the other hand, when the tape cartridge is in use, i.e., the tapecartridge is loaded in the digital audio tape player, the slider 7 ismoved from the projected position, as shown in FIG. 1, towards theretracted position against the biasing spring 17, opening the bottomregion of the transverse front window 4 and the front cover 6 issubsequently pivoted about the common axis of the pivot pins 15 from theclosed position towards the opened position. As the front cover 6 sopivoted approaches the opened position, the operating ribs 16 arebrought into abutment with the engagement pawls 13 and the continuedpivot of the front cover 6 towards the opened position results in a pullof the traction arms 12 in a direction close towards the front window 4and, therefore, the lock member 9 integral with the traction arms 12 ismoved from the lock position towards the unlock position against thewire spring 10. It is to be noted that, since each of the free ends ofthe hinge arms 6b of the front cover is partially inclined or rounded,as shown by 6d in FIG. 1 so, as to permit the free end of the associatedstopper rod 14 to provide no obstruction to the passage of the free endof the corresponding hinge arm 6b, the pivotal movement of the frontcover 6 from the closed position towards the opened position will not behampered.

It may, however occur, that, when the tape cartridge is inadvertentlydropped onto the ground surface, one or both of the free ends of thestopper rods 14 may slide along the free end faces of the respectivehinge arms 6b of the front cover 6 and then protrude into gaps eachbetween the associated hinge arm 6b and the adjacent side wall sectionof the casing 1. Once this occurs, the free end portions of the hingearms 6b may be undesirably deformed outwardly of the casing 1. Thispossibility can be advantageously eliminated according to a secondpreferred embodiment of the present invention which will now bedescribed with particular reference to FIGS. 6 to 9.

According to the second preferred embodiment of the present invention,the tape cartridge is provided with means 22 for suppressing a lateraldisplacement of the free ends of the stopper rods 14 relative to theassociated free ends of the hinge arms 6b. So far, as illustrated inFIGS. 6 to 9, this lateral displacement suppressing means 22 comprises afirst lateral protuberance 20 formed on each of the free ends of thestopper rods 14 so as to protrude along an axis laterally offset fromthe longitudinal axis of the respective stopper rod 14, and a secondlateral protuberance 21 formed on each of the free ends of the hingearms 6b so as to protrude along an axis laterally offset from thelongitudinal axis of the respective hinge arm 6b, but in a senseopposite to the axis along which the first lateral protuberance 20protrudes.

Thus, it will readily be understood that, not only can the lateraldisplacement of the stopper rods 14 in a direction laterally inwardly ofthe casing 1 be blocked by the second lateral protuberances 21 thenreceiving the first lateral protuberances 20, but the lateraldisplacement of the hinge arms 6b integral with the front cover 6 in adirection laterally outwardly of the casing 1 can also be blocked by thelateral protuberances 20 then receiving the second lateral protuberances21. Therefore, even though an intense impact acts on the tape cartridge,the possibility of one or both of the free ends of the stopper rods 14plunging into the gaps each between the associated hinge arm 6b and theadjacent side wall section of the casing 1 can advantageously beminimized.

Each of the side openings 19 through which the associated stopper rods14 move during the movement of the lock member 9 between the unlockedand locked positions has been described as defined at the steppedshoulder in each side wall of at least the upper casing half la.Specifically, as best shown in FIGS. 7 and 10, each of the side wall ofthe upper casing 1a is, when viewed from top as shown in FIG. 7,constituted by an inner side wall segment 23 adjacent the front window 4and an outer side wall segment 24 extending parallel to, but offsetlaterally relative to the inner side wall segment 23, and a gate wall glying parallel to any one of the inner and outer side wall segments 23and 24 and connecting the both together. The gate wall g has the sideopenings 19 defined therein for the passage of the corresponding stopperrod 14 therethrough.

The position of the gate wall g in each of the side walls of the uppercasing 1a is so chosen that, so long as the tape cartridge is not in usewith the lock member 9 held in the lock position, the free end of eachstopper rod 14 is situated within the respective side opening 19. Inthis case, the extent to which the inner and outer side wall segments 23and 24 are laterally offset relative to each other is so chosen as tocorrespond to the thickness of each stopper rod 14 or, alternatively,each side opening 19 may be so chosen as to have a width correspondingto the thickness of the associated stopper rod 14, thereby to avoid anylateral rattling motion of the stopper rod 14 within the associated sideopening 19.

Each side opening 19 may be of a generally closed rectangularconfiguration or, alternatively, it may be of a generally U-shapedconfiguration opening downwardly towards the corresponding side wall ofthe lower casing 1b. In the illustrated embodiments, the side opening 19is of the generally U-shaped configuration opening downwardly towardsthe corresponding side wall of the lower casing 1b and, therefore, inthe event that the free ends of the stopper rods 14 abruptly andvigorously abut against the free end faces of the hinge arms 6b of thefront cover 6, a bending moment indicated by M in FIG. 6 acts to bendthe free ends of the hinge arms 6b downwardly towards the lower casinghalf 1b. To avoid this possibility, a bench piece 26 is formed on anupper edge of each side wall of the lower casing 1b at a locationimmediately below the associated side opening 19 to support theassociated stopper rod 14 from below thereby to avoid any possiblebending of the support rod 14.

It is to be noted that, although in any one of the foregoing embodimentsof the present invention, the stopper rods 14 have been described asemployed for each side of the tape cartridge, only one stopper rod 14may be employed for either side of the tape cartridge. It is also to benoted that an undesirable movement of the lock member 9 towards theunlock position may also be suppressed even when at least a similarbench piece is formed on the associated operating rib 16 integral withthe front cover 6.

While respective mating faces of the first and second lateralprotuberances 20 and 21 forming the lateral displacement suppressingmeans 22, which confront with each other in a direction transverse tothe associated side wall of the casing 1, are inclined so as to extendparallel to each other, as best shown in FIG. 7, the mating faces of thefirst and second lateral protuberances 20 and 21 may be right-angledrelative to the associated stopper rod 14 and the associated hinge arm6b, as best shown in FIG. 11. Alternatively, as shown in FIGS. 12 and13, the lateral displacement suppressing means 22 may be constituted bya first inclined end face 27 defined in the free end face of the stopperrod 14 and a second inclined end face 28 defined in the free end face ofthe hinge arm 6b and extending parallel to the first inclined end face27.

Again alternatively, as best shown in FIGS. 14 and 15, the lateraldisplacement suppressing means 22 may be constituted by a semi-sphericalor conical protuberance 29 formed on the free end face of one of thestopper rod 14 and the hinge arm 6b so as to protrude towards theassociated hinge arm 6b or the associated stopper rod 14, and a pocket30 formed on the free end face of the other of the stopper rod 14 andthe free end face of the hinge arm 6b and having a shape complemental tothe shape of the semi-spherical or conical protuberance 29. The lateraldisplacement suppressing means 22 constituted by the shaped protuberance29 and the complementally shaped pocket 30, as shown in FIGS. 16 and 17,is particularly advantageous in that, even though the free end of thestopper rod 14 is substantially displaced laterally relative to the freeend of the associated hinge arm 6b at the moment the stopper rod 14 isbrought into abutment with the associated hinge arm 6b, the shapedprotuberance 29 is received within the complementally shaped pocket 30thereby to assuredly avoid any possible plunging of the stopper rod 14into the gap between the associated hinge arm 6b and the adjoining sidewall (inner side wall segment 23) of the upper casing half 1b.

In an embodiment shown in FIGS. 16 and 17, the free end of the hinge arm6b integral with the front cover 6 is formed with a thin-walledextension 6c protruding outwardly therefrom towards the associatedstopper rod 14 so that, so long as the front cover 6 is held in theclosed position, the extension 6c is received within the side opening 19together with the free end of the associated stopper rod 14. Accordingto the embodiment of the lateral displacement suppressing means 22,shown in FIGS. 16 and 17, so long as the tape cassette is not in usewith the front cover 6 consequently held in the closed position, anyundesirable lateral displacement of both of the respective free ends ofthe stopper rod 14 and the corresponding hinge arm 6b can advantageouslyminimized or substantially eliminated since both of the free end of thestopper rod 14 and the extension 6c of the corresponding hinge arm 6bare enclosed within the associated side opening 19.

FIG. 18 illustrates a modified form of a deformation preventing meansfor preventing any possible deformation of each of the hinge arms 6b ofthe front cover 6. This deformation preventing means exhibits itsfunction and effect when the tape cassette is not in use, that is, whenthe front cover 6 is held in the closed position and the slider 7 isheld in the projected position. As shown therein, a lower face of therespective hinge arm 6b is formed with a generally L-sectioned groove31a while an upper face of the side wall 7b of the slider 7 is formedwith a mating rib 31b engageable in said L-sectioned groove 31a, therebyto avoid any possible lateral deformation of one of the hinge arm 6b andthe side wall 7b relative to the other of the hinge arm 6b and the sidewall 7b.

The effect to avoid the possible lateral deformation of one of the hingearm 6b and the side wall 7b relative to the other of the hinge arm 6band the side wall 7b can be advantageously enhanced if, as shown in FIG.19, that portion of the hinge arm 6b where the L-shaped groove 31a isformed and confronts the rib 31b is thick-walled to have an increasedthickness.

Thus, according to the present invention, the stopper rods 14 protrudingfrom the side plates 9a of the lock member 9 are designed to receive therear end faces of the respective hinge arms 6b integral with the frontcover 4 so as to avoid an arbitrary movement of the lock member 9towards the unlock position when the front cover 4 is in the closedposition. Accordingly, when the tape cartridge is inadvertently droppedonto the ground surface with a drastic impact consequently actingthereon, the lock pawls 11 will not disengage from the associatedtoothed lock wheels 8 and, therefore, any possible loosening of thelength of magnetic tape can advantageously be avoided. This in turnsubstantially eliminates the possibility of the digital audio tapeplayer malfunctioning as a result of entanglement of the loosened lengthof magnetic tape around component parts of the player and/or by anyother reason.

The provision of the lateral displacement suppressing means 22 definedin the free end faces of the stopper rods 14 and the mating free endfaces of the hinge arms 6b integral with the front cover 4 makes itpossible to avoid any possible lateral displacement of the stopper rods14 relative to the associated hinge arms 6b which would otherwise resultin an undesirable plunge of the stopper rods 14 into gaps between thehinge arms 9b and the side walls of the tape cartridge and/or anundesirable lateral deformation of the hinge arms 6b.

The use of each side wall of the tape cartridge which is comprised ofthe inner and outer wall segments 23 and 24 with the respective sideopening 19 defined therebetween ensures any possible lateraldisplacement of one or both of the hinge arms 6b and the stopper rods 14inwardly for outwardly with respect to the tape cartridge.

Also, according to the present invention, the possible lateraldeformation of one of the hinge arm 6b and the side wall 7b relative tothe other of the hinge arm 6b and the side wall 7b can be substantiallyeliminated by the use of the L-shaped groove 31a, formed in one of thehinge arm 6b and the side wall 7b, and the rib 31b formed in the otherof the hinge arm 6b and the side wall 7b, thereby to ensure an constantalignment of the respective stopper rod 14 with the associated hinge arm6b which is necessary to assuredly avoid the undesirable movement of thelock member 9 towards the unlock position.

Although the present invention has been described in connection with thepreferred embodiments thereof with reference to the accompanyingdrawings, it is to be noted that various changes and modifications areapparent to those skilled in the art. Such changes and modifications areto be understood as included within the scope of the present inventionas defined by the appended claims, unless they depart therefrom.

What is claimed is:
 1. A tape cartridge which comprises:a generally rectangular box-like casing including rectangular top and bottom walls, a pair of side walls and a rear wall, all assembled together to represent a generally rectangular flat box-like configuration with a tape chamber defined therein, said casing having a front opening opposite to said rear wall; a front cover hinge supported having a pair of hinged arms pivotally coupled to said respective side walls for pivotal movement between opened and closed positions, said front opening being opened and closed when said front cover is in the opened and closed positions, respectively; first and second reels rotatably housed within said tape chamber, with opposite ends of a length of magnetic tape being secured to said first and second reels, respectively, each of said reels having a toothed lock wheel rotatable together therewith; a hub lock mechanism housed within said tape chamber and including a generally elongated lock member movable between locked and unlocked positions in a direction transverse to said front cover, said lock member including a bridge plate and lateral side plates, and a spring element for biasing said lock member towards said locked position, said lock member having lock pawls engageable with said toothed lock wheels to lock the respective reels when the lock member is in said locked position, said lock member also having traction arms protruding from each of said lateral side plates of said lock member in a direction perpendicular to said lock member and towards said hinged arms, said traction arms being operatively coupled with said hinged arms such that, as said front cover is pivoted from a closed position towards an opened position, said lock member is pulled from said locked position towards said unlocked position against said spring element; and at least one stopper rod protruding from at least one of said lateral side walls of said lock member in a direction perpendicular to said lock member and towards said front opening in alignment with a corresponding one of said hinged arms, said at least one stopper rod having a free end spaced a given distance from a free end of said corresponding hinged arm when said front cover is in said closed position, such that any movement of said lock member over said given distance while said front cover in said closed position will not result in a disengagement of said lock member as a result of said free end of said at least one stopper rod engaging said corresponding hinged arm.
 2. A tape cartridge which comprises:a generally rectangular box-like casing including rectangular top and bottom walls, a pair of side walls and a rear wall, all assembled together to represent a generally rectangular flat box-like configuration with a tape chamber defined therein, said casing having a front opening opposite to said rear wall; a front cover hinge supported having a pair of hinged arms pivotally coupled to said respective side walls for pivotal movement between opened and closed positions, said front opening being opened and closed when said front cover is in the opened and closed positions, respectively; first and second reels rotatably housed within said tape chamber, with opposite ends of a length of magnetic tape being secured to said first and second reels, respectively, each of said secured to said first and second reels, respectively, each of said reels having a toothed lock wheel rotatable together therewith; a hub lock mechanism housed within said tape chamber and including a generally elongated lock member movable between locked and unlocked positions in a direction transverse to said front cover, and a spring element for biasing said lock member towards said locked position, said lock member having lock pawls engageable with said toothed lock wheels to lock the respective reels when the lock member is in the locked position, said lock member also having traction arms protruding from opposite ends of said lock member in a direction perpendicular to said lock member and towards said hinged arms, said traction arms being operatively coupled with said hinged arms such that, as said front cover is pivoted from a closed position towards an opened position, said lock member is pulled from the lock position towards the unlock position against the spring element; at least one stopper rod protruding from a corresponding one of the opposite ends of the lock member in a direction perpendicular to the lock member and towards the front opening in alignment with a corresponding one of the hinge arms, said stopper rod having a free end positioned in close proximity to the corresponding hinge arm, when the front cover is in the closed position thereby to keep the lock member immovable; and a lateral displacement suppressing means defined in part in the free end of the stopper rod and in part in the free end of the corresponding hinge arm for avoiding a deformation of the stopper rod inwardly of the casing.
 3. The tape cartridge as in claim 2 wherein said lateral displacement suppressing means comprises a first lateral engagement defined in the free end of the stopper rod and a second lateral engagement defined in the free end of the corresponding hinge arms, said first and second lateral engagements being laterally offset in position relative to each other with respect to a longitudinal axis of any one of the stopper rod and the corresponding hinge arm.
 4. The tape cartridge as in claim 2, wherein said lateral displacement suppressing means comprises a first inclined face defined at the free end of the stopper rod and a second inclined face defined at the free end of the corresponding hinge arm, said first and second inclined faces being complemental to each other and inclined relative to a longitudinal axis of any one of the stopper rod and the corresponding hinge arm.
 5. The tape cartridge as in claim 2, wherein said lateral displacement suppressing means comprises a protuberance protruding outwardly from one of the free ends of the stopper rod and the corresponding hinge arm and a pocket defined in the other of the free ends of the stopper rod and the corresponding hinge arm for receiving the protuberance therein.
 6. The tape cartridge according to claims 1 or 2, wherein said casing also includes an inner side wall segment for restricting an inward displacement of said at least one stopper rod and each hinged arm when said front cover is in the closed position.
 7. The tape cartridge as in claim 6, wherein said casing also includes an outer side wall segment for restricting an outer displacement of said at least one stopper rod and each hinged arm when said front cover is in the closed position.
 8. The tape cartridge according to claims 1 or 2, wherein said casing also includes an outer side wall segment for restricting an outer displacement of said at least one stopper rod and each hinged arm when said front cover is in the closed position.
 9. The tape cartridge claims 1 or 2, further comprising a generally U-sectioned slider forming a front area of the bottom wall and supported for movement in a direction perpendicular to the front cover for selectively opening and closing a bottom region of the front opening, said slider having upright side wall elements aligned with the respective hinged arms integral with said front cover, each of said side wall elements having a first engagement defined therein while each of said hinged arms has a second engagement defined therein for engagement with the first engagement to prevent said hinged arms from being outwardly deformed. 